If this included a definition of a vehicle, and asked if a vehicle was in the park, I'd expect consistent answers outside of the oddball aircraft and space station questions.
I'd note my local park has such a rule, and the sign has pictures of what are and are not allowed, including a picture of a drone.
Here's a common example from real life: "No pornography". Even SCOTUS famously couldn't define obscenity ("I know it when I see it")
“I know it when I see it” was in reference to _hardcore pornography_, not obscenity. The Miller Test deals with obscenity perfectly well.
If you were to open a subreddit, or walk up to a library computer/print shop counter and saw "No Pornography" under rules - would you be unable to figure out what's being asked of you? If so, then that seems like a complete thought and a perfectly comprehendible rule to me.
What happens if the sign in your park was made in 1995, when drones, electric scooters, and electric bikes didn't exist or were not commonly used?
It's not possible to list every possible vehicle in existence, and to keep such a list updated. There are all sorts of weird things like electric unicycles, that most people haven't come across.
It’s typically shades of gray and requires judgement, discretion.
And consequences of breaking a rule or law require even more judgement.
The world isn’t a “smart”contract.